Precast thermal insulation for flowlines and risers

ABSTRACT

Precast thermal insulation for flowlines and risers includes an outer protective shell that has an exterior surface and an interior surface that together define a volume within the outer protective shell. High elongation syntactic foam insulation is located within the volume, and comprises microsphere and a semi-rigid epoxy plastic resin binder. The precast thermal insulation permits advanced materials to be used for risers and flowlines, including highly flexible systems for installation by reeling.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from the provisional application designated Ser. No. 61/060,580 filed Jun. 11, 2008 and entitled “Precast Thermal Insulation for Flowlines and Risers”. This application is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to thermal insulation for flowlines and risers, and in particular to the high performance syntactic foam thermal insulation for offshore flowlines and production risers.

Epoxy/glass syntactic foam has been supplied to the offshore industry for over ten years as the premium solution to insulating subsea equipment under the most demanding conditions of depth and temperature.

There is a need for improved thermal insulation for flowlines and risers.

SUMMARY OF THE INVENTION

Precast thermal insulation for flowlines and risers includes an outer protective shell that has an exterior surface and an interior surface that together define a volume within the outer protective shell. High elongation syntactic foam insulation is located within the volume, and comprises microsphere and a semi-rigid epoxy plastic resin binder.

The precast thermal insulation permits advanced materials to be used for risers and flowlines, including highly flexible systems for installation by reeling.

In one embodiment the outer protective shell is semi-cylindrical and includes high elongation syntactic foam. The shell may be precast in the factory. The precasting permits rapid manufacture and curing of materials systems that generally cannot be readily cast directly onto pipe or applied by mixing and pouring in the field. The precast elements are then secured (e.g., bonded) to the pipe, for example, with a fast-curing but highly flexible epoxy adhesive. The resulting construction is as rugged and efficient as factory-coated coatings, but has the advantage of being assembled at the customer's reelbase, shipyard, on board ship, or wherever is most convenient and cost-effective.

By separating the factory casting operation from the field installation activity, the present invention facilitates the use of advanced epoxy chemistry for greater flexibility, superior strength, and higher temperature resistance. It also has the advantage of offering the opportunity for increased local content. The actual assembly of the insulation sleeves onto the pipe can be performed quickly and easily on site by unskilled labor with simple equipment. Pipe handling is reduced, lead time is shortened, and delivery is fast and dependable.

Insulating properties of the precast thermal insulation are equal to or better than any competing “wet” insulation material. Depth rating to about 10,000 feet and temperature resistance of about 250° F. or higher are available. Elongation-to-break is no less than about 20%. Typical thermal conductivity is about 0.08 Btu/hr-ft-F. A variety of different materials and constructions can be supplied.

These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cut-away illustration of a flowline that includes precast thermal insulation; and

FIG. 2 is a cross-sectional view along lines 1-1 of the flowline that includes the precast thermal insulation of FIG. 1.

DESCRIPTION OF THE INVENTION

FIG. 1 is a partially cut-a-way illustration of an insulated flowline 10 that includes a plurality of precast thermal insulating elements 12-17 radially mounted around a flowline 20. The flowline may be, for example, a steel pipe that has a diameter of about 4 to 10 inches and a wall thickness typically 0.25 to 0.5 inches. Each of the precast thermal insulating elements includes outer skin (e.g., fiberglass) that may be is backed by a fibrous plastic liner. Each element includes an interior surface that is located radially proximate to the flowline, and an exterior surface that is radially distal from the flowline. The interior and exterior surfaces of each insulating element form a volume, which contains high elongation syntactic foam insulation comprising microspheres and a semi-rigid epoxy plastic resin.

Each of the precast thermal insulating elements is preferably semi-cylindrical, and secured to the flowline 20. For example, the elements 12-17 may be secured to the flowline 20 with a fast-curing but highly flexible epoxy adhesive 18.

FIG. 2 is a cross-sectional view along line 1-1 of the insulated flowline 10 that includes the precast thermal insulation of FIG. 1.

Manufacturing techniques are discussed in U.S. Pat. Nos. 7,121,767, 6,827,110 and 6,058,979 assigned to the assignee of the present invention, which are hereby incorporated by reference.

Pre-casting the elements introduces a degree of freedom in the manufacturing process that enables, for example, the use of special-purpose thermoset or thermoplastic polymeric materials that would otherwise not be practical.

Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention. 

1. Precast thermal insulation for flowlines and risers, comprising: an outer protective shell that has an exterior surface and an interior surface that together define a volume within the outer protective shell; and high elongation syntactic foam insulation located within the volume, comprising microsphere and a semi-rigid epoxy plastic resin binder.
 2. The precast thermal insulation of claim 1, wherein the outer protective shell is fiberglass.
 3. The precast thermal insulation of claim 2, further comprises macrospheres within the volume.
 4. The precast thermal insulation of claim 2, wherein the outer protective shell is semi-cylindrical. 